1. Field of the Invention
This invention relates to fans and, more specifically, relates to a centrifugal fan having an inter stage and/or an after or discharge stage.
2. Summary of the Prior Art
Inter stage and after stage devices for centrifugal fan systems are known and have been utilized with fans and fan systems for many years. It is also known to provide blading or shrouds for these devices which tend to turn the flow of the centrifugal fan stage discharge. An attempt has been made, in many instances, in the design of the blading or shrouding, to obtain a smooth transition at the discharge from the centrifugal fan. This has taken, generally, the form of a separate structure to define the desired air flow channel, leaving an intermittent or discontinuous guided flow path for the centrifugal fan discharge. This causes losses and inefficiencies of some magnitude for the discharge flow from the fan system.
Accordingly, it is an object of the invention to provide a guidance arrangement for the flow of discharge air from a fan having improved static recovery and efficiency.
It is a further object of the invention to provide guidance blading operative to smoothly guide air axially towards a discharge port or a centrifugal fan eye.
It is an additional object of the invention to provide continuous blading for an inter stage or after stage which turns the fan discharge from an outward tangential direction to an axial, radial direction.
It is a still further object of the invention to incline the outer ends of stage blades in an axial direction to provide guidance for the fan discharge as it moves to a fan eye or central discharge point.
It is an even further object of the invention to angle the blade tip ends of continuous blades axially to accommodate a streamlined flow for a motor-fan system.
It is also an object of the invention to angle the blade tips end, at an angle axially to accommodate the operating point of the motor-fan system.